1. Field
The present disclosure relates to methods of manufacturing a carbon and fibrous polymer composition suitable for use in electrodes and other components in electrical devices, such as electric double layer capacitors.
2. Technical Background
High density energy storage devices, such as electric double layer capacitors, have been the subject of considerable research. An electric double layer capacitor or EDLC is a type of capacitor that typically contains carbon electrodes separated by a porous separator, current collectors, and an electrolyte solution. When an electric potential is applied to an EDLC, ionic current flows due to the attraction of anions to the positive electrode and cations to the negative electrode. This ionic current flow generates an electric charge that is stored at the interface between each polarized electrode and the electrolyte solution.
The design of an EDLC can vary depending on the intended application and can include, for example, standard jelly roll designs, prismatic designs, honeycomb designs, hybrid designs, or other designs known in the art. The energy density and the specific power of an EDLC can be affected by the properties of the components comprising the EDLC, including the electrode and the electrolyte utilized. With respect to the electrode, high surface area carbons, carbon nanotubes, other forms of carbon, and composite materials have conventionally been utilized in manufacturing such devices.
Carbon materials for EDLC electrodes are traditionally coated and/or deposited onto a current collector or other substrate. To produce stable and uniform dispersions, such carbon materials are typically mixed with a binder, such as, for example, polyvinylidene fluoride (PVDF). For example, in a conventional process, a slurry of a carbon material and a binder, such as, for example, PVDF, can be coated onto a graphite coated aluminum current collector, wherein the slurry coating is typically exposed to heat and/or vacuum to remove any liquid that can be present. The use of a binder material, such as PVDF, can increase the processing time required to prepare an electrode, lead to contamination, and can result in large internal resistance, thus decreasing the performance achievable for a given electrode structure.
Thus, there is a need to address the aforementioned problems and other shortcomings associated with the traditional electric double layer capacitors. These needs and other needs are satisfied by the carbon compositions and methods of the present invention.